Method and apparatus for treatment of discogenic pain

ABSTRACT

A method of treating discogenic back pain in a patient includes the steps of acquiring an image of at least a portion of the patient&#39;s spine, locating the spinal disc causing the back pain, and identifying a treatment volume encompassing at least a portion of the spinal disc. The method further includes prescribing a radiation dose to be delivered to the treatment volume, providing a radiation therapy machine, positioning the patient in the radiation therapy machine, programming the radiation therapy machine to deliver the radiation dose to the treatment volume, and delivering the radiation dose to the treatment volume.

FIELD OF THE INVENTION

The present invention relates to the use of radiation to treat back painsuch as that caused by spinal disc disorders. In particular, the presentinvention relates to an apparatus for and method of treatment ofdiscogenic pain using radiation.

BACKGROUND OF THE INVENTION

The spinal column is comprised of interlocking vertebrae separated byintervertebral discs. The spine provides load-bearing support forone-half of the body's mass and it protects the nerves of the spinalcolumn. The intervertebral discs provide shock absorption and facilitatethe bending of the spine.

The combination of the vertebrae and discs at each vertebral segmentallows for motion of the spine, in particular, flexing, rotation, andextension. The motion and support functions of the spine, in combinationwith the many interlocking parts and nerves associated with the spinalcolumn, can result in back pain due to various reasons.

Most back pain arises in the lumbar region of the back. Back pain mayresult from strain on the back due to overexertion or may be due to poorposture or an injury to the spine. Chronic back pain is often due to adisorder originating in or from an intervertebral disc (i.e. discogenicpain). Such conditions can include bulging, herniated, or ruptureddiscs. A bulging, herniated or ruptured disc can trigger a response fromproximate nerves, causing the pain sensation. Even after a herniateddisc heals, the anatomy of the disc may not return to normal and maycontinue to cause pain. Even in the case where a disc is not herniated,chronic pain may present itself as people age because the annulusfibrosus begins to decay and the resulting small tears in the wall areinfiltrated by nerves and blood vessels, causing pressure and chronicpain.

Intervertebral discs have an outer annulus fibrosus that surrounds theinner nucleus pulposus. A bulging or herniated disc is a situation wherethe nucleus pulposus herniates outward through the annulus fibrosus. Theannulus fibrosus contains nerves, and the nociceptors andmechanoreceptors associated with the nerves respond to the discherniation by providing a pain sensation. The pain receptors areconcentrated along the posterior wall of the disc and the pain mayresult from the disc herniation but may also result from internal discdisruption, possibly involving partial tears in the multi-layeredannulus fibrosus. Pain may also result from a disc fragment that remainsexterior to the annulus fibrosus after the herniated disc recedes.

There are several non-surgical approaches that may be used to treat backpain. These include heating the affected area, certain types ofexercise, medication, and electrical nerve stimulation. However,non-surgical treatments are often ineffective in treating chronic backpain.

There are a number of minimally invasive surgical procedures that areused to treat back pain with varying degrees of success. Intradiscalelectrothermal therapy (IDET), also called intradiscal electrothermalannuloplasty, involves the application of heat directly to the inside ofthe disc via a needle that is inserted into the disc and heated at thedesired location. Radiofrequency annuloplasty is another surgical methodin which radiofrequency thermal energy is delivered to the affected areaof the disc via a needle. Laser discectomy involves using a laser tovaporize a portion of the nucleus pulposus to decrease pressure in thedisc. Thermal discoplasty utilizes a needle to deliver heat to thenucleus pulposus to decrease the pressure in the disc.

Other conventional surgical approaches are less minimally invasive.These include discectomy, in which all or part of the disc is removed inan effort to reduce pressure on the affected nerves; disc replacement,in which the disc is replaced with an artificial disc; and spinalfusion, in which the affected disc is removed and the two adjoiningvertebrae are fused together.

Certain of the conventional treatments are designed to ablate or removedisc material to reduce the pressure in the disc. These include thediscectomy procedures, including laser discectomy and radiofrequency orthermal discoplasty, also referred to as disc nucleoplasty. Othertechniques attempt to treat the disc directly using thermal orradiofrequency energy, such as the IDET and radiofrequency annuloplastyprocedures. It is not known exactly why the procedures that attempt todirectly treat the disc, such as IDET, work. It is theorized that themethods may aid in the repair of tears in the annulus fibrosus, but theprocedures may also destroy nociceptors in the treated area, thusdisrupting their ability to sense pressure and transmit pain.

Each of the conventional approaches for treating back pain has certaindisadvantages. In particular, each of the surgical approaches, eventhose that are minimally invasive, require penetration of the skin withsurgical instruments to approach the area to be treated, even where theprimary surgical instrument is a catheter or needle. Further, there arerisks associated with the conventional surgical approaches that areinherent in any operation on the spine. Further still, the cause of theback pain may be inoperable due to the anatomy of the spine. Finally,all of the present approaches to treatment of back pain exhibit varyingdegrees of success, especially where the precise reason why the selectedtreatment method accomplishes its goal is not exactly known. Presently,spinal fusion, the most invasive of the conventional surgicalapproaches, is the preferred approach when less invasive methods are notsuccessful.

There is a need for a back pain treatment that addresses one or more ofthe disadvantages of conventional approaches. In particular, there is aneed for a back pain treatment that is non-invasive, less expensive thanconventional surgical treatments, and able to treat back pain that isotherwise inoperable.

It would be desirable to provide a system and/or method that satisfiesone or more of the aforementioned needs or provides other advantageousfeatures. Other features and advantages will be made apparent from thepresent specification. The teachings disclosed extend to thoseembodiments that fall within the scope of the claims, regardless ofwhether they accomplish one or more of the aforementioned needs.

SUMMARY OF THE INVENTION

The invention relates to a method of treating discogenic back pain in apatient. The method includes the steps of acquiring an image of at leasta portion of the patient's spine, locating the spinal disc causing theback pain, and defining a treatment volume encompassing a portion of thespinal disc. The method further includes the steps of prescribing aradiation dose to be delivered to the treatment volume, providing aradiation therapy machine, and positioning the patient in the radiationtherapy machine. Further still, the method includes the steps ofprogramming the radiation therapy machine to deliver the radiation doseto the treatment volume and delivering the radiation dose to thetreatment volume.

The invention further relates to a discogenic back pain treatment devicehaving a patient support, a radiation source, and a radiation deliverymechanism coupled to the radiation source. The discogenic back paintreatment device further includes a treatment planning computer adaptedto control the radiation delivery mechanism and programmed to deliverradiation from the radiation source to a treatment volume encompassingat least a portion of a spinal disc.

The invention further relates to a method for treating pain resultingfrom a herniated spinal disc using the discogenic back pain treatmentdevice. The method includes the steps of contacting a medical clinichaving a radiation therapy machine to schedule a visit, visiting themedical clinic, assuming a position on the patient support, andinactivating one or more nerves in a treatment volume encompassing atleast a portion of the herniated disc by receiving radiation from theradiation source to the treatment volume.

The invention is capable of other embodiments and of being practiced orcarried out in various ways. Alternative exemplary embodiments relate toother features and combinations of features as may be generally recitedin the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingdrawings, wherein like reference numerals refer to like elements, inwhich:

FIG. 1 is a side elevation view of a spine;

FIG. 2 is a sectional view of a portion of the lumbar portion of a spineincluding an intervertebral disc;

FIG. 3 is a sectional view of a portion of the lumbar portion of a spineincluding a partially herniated intervertebral disc;

FIG. 4 is a sectional view of a portion of the lumbar portion of a spineincluding an intervertebral disc; and

FIG. 5 is a schematic perspective view of a radiation therapy machinewith a cut-away portion showing the gantry.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, the spine 10 includes vertebrae 12 separated byintervertebral discs 14. A vertebral canal 16 extends along successivevertebrae and houses the spinal cord (not shown).

Referring to FIG. 2, an intervertebral disc 14 includes an inner nucleuspulposus 18 and an outer annulus fibrosus 20. The annulus fibrosus 20 ismade up of a number of bands that are arranged in a series of concentriclayers to retain the nucleus pulposus 18 and aid in resisting otherforces placed on the spine 10. In the lumbar portion of the spine 10,the cauda equina 22 runs through the vertebral canal 16. Spinal nerves24 extend outwardly from the cauda equina 22, with nerve roots 26proximate the cauda equina 22. While a lumbar vertebra and associateddisc are shown in FIGS. 2-4, the invention is equally applicable toother vertebrae and discs in the spine.

The outer portion of the annulus fibrosus 20 is innervated by thesinuvertebral nerve (not shown). The sinuvertebral nerve also innervatesother structures in the epidural space. As discussed above, thenociceptors in the annulus fibrosus 20 transmit pain due to herniationof the intervertebral disc 14 or other discogenic causes. For example,as shown in FIG. 3, the nucleus pulposus 18 may bulge outward, possiblydue to degradation in the fibers making up the concentric rings of theannulus fibrosus 20. The bulging disc 14 may apply pressure on nervesproximate the bulge 28. Such pressure may result in radiating pain downa patient's leg. The entry into the vertebral canal 16 of theintervertebral disc 14 material may also cause toxic damage to thenerves in the area, resulting in pain.

Referring to FIG. 4, the nociceptors 30 populating the outer portion ofthe annulus fibrosus 20 may transmit impulses resulting in the sensationof pain. Such nociceptors 30 are typically concentrated along theposterior wall of the disc 14. A treatment volume 32 may be identifiedthat contains a number of the nociceptors 30 causing the pain sensation.Depopulation of the nociceptors 30 in the treatment volume 32 may resultin a decrease or cessation of the pain originating from the treatmentvolume 32. It is theorized that certain conventional minimally invasiveprocedures, such as IDET, result in the thermocoagulation of nociceptorswithin the walls of the intervertebral disc being treated and thereforeresult in the reduction of pain. The treatment volume 32 may alsoinclude a portion of the intervertebral disc where blood vessels haveinvaded, such as the area of a tear in the annular wall of the disc.Such invading vasculature can cause back pain.

Referring to FIGS. 4 and 5, according to an exemplary embodiment of theinvention, a radiation therapy machine 40 is used to deliver radiationto the treatment volume 32 in order to treat unremitting back pain. Theradiation is intended to depopulate or inactivate the nerves providingthe pain sensation, eliminate invading vasculature, and/or shrink discmaterial to reduce pressure in the area. In a preferred embodiment, theradiation therapy machine 40 is designed to utilize conformalradiotherapy to deliver the radiation to the treatment volume 32. Due tothe sensitive structures proximate the treatment volume 32, inparticular the spinal cord and cauda equina, ideally a form of imageguided radiation therapy is utilized. One such image guided radiationtherapy machine is the TomoTherapy HI-ART® system available fromTomoTherapy Incorporated of Middleton, Wis.

In an exemplary embodiment, where an image-guided radiation therapyapproach is utilized, the radiation therapy machine 40 has a rotatinggantry 44 within a housing 42. An x-ray source 46 and correspondingdetector 48 used for acquiring data to construct CT images of thepatient are mounted on the gantry 44 along with a radiation deliverymechanism 50 used to deliver the desired dose to the treatment volume32. The radiation delivery mechanism 50 is a rotating radiation outputport on the gantry 44 in the embodiment of FIG. 5. A radiation source,e.g. linear accelerator or Cobalt-60 source, generates the radiationthat is delivered via the radiation delivery mechanism 50. A patientsupport, shown as table 52, is configured to support the patient (notshown) within the rotating gantry 44 and to slide the patient throughthe open center portion of the gantry 44 in order to acquire a spiral CTscan of the patient simultaneously with the delivery of radiation in ahelical fashion to the desired treatment volume 32. A computerworkstation 54 may be utilized to control the radiation therapy machine40 as well as to display the acquired images.

Other types of radiation therapy or radiosurgery equipment may also beutilized to deliver a prescribed radiation dose to the treatment volume32. Examples of such devices include linear accelerators and x-raymachines. One machine using a linear accelerator that may be useful in apreferred embodiment is a CYBERKNIFE® stereotactic radiosurgery systemthat utilizes a radiation delivery mechanism in the form of a roboticarm to deliver a radiation beam from many different angles to the targetarea. The CYBERKNIFE® stereotactic radiosurgery system is available fromAccuray Incorporated of Sunnyvale, Calif.

In order to determine whether the radiation therapy machine 40 may beutilized to treat lower back pain, the cause of the pain must first bediagnosed. Various methods for performing such a diagnosis are known,and include discography, which involves the injection of a radio-opaquedye into the spinal disc, followed by an x-ray image to determinewhether the disc at issue is herniated or degraded in some way. Acomputed tomography (CT) or magnetic resonance imaging (MRI) scan mayalso be used to reconstruct a three-dimensional image of the areathought to be causing the pain to identify the condition causing thepain. Other types of imaging procedures, such as PET or SPECT, may alsobe utilized to identify the intervertebral disc causing the pain.

Referring again to FIG. 4, once the disc causing the pain has beenidentified along with the reason for the pain, the treatment volume 32may be defined. In an exemplary embodiment, the treatment volume 32 is athree-dimensional region encompassing the posterior side of the annulusfibrosus 20 containing the offending nociceptors and/or the inflamedarea causing the pain.

Once the treatment volume 32 has been defined, the physician treatingthe patient may prescribe a radiation therapy plan. In an exemplaryembodiment, the radiation therapy plan or “treatment plan” involvesdelivering a specified radiation dose to the treatment volume, ideallyusing a stereotactic approach in order to spare issues outside of thetreatment volume 32 to the extent possible. The radiation may bedelivered to the treatment volume 32 in a single treatment or may befractionated to deliver a portion of the prescribed dose over the courseof several treatments. In an alternative embodiment, a fluid such as adye may be injected into the disc space to concentrate the effect of theradiation delivered to the treatment volume.

In an exemplary embodiment, the workstation 54 is a treatment planningcomputer that is loaded with treatment planning software that may beused to calculate a suitable method for delivering the prescribedradiation dose to the treatment volume 32. In a preferred embodiment,the radiation is delivered from multiple positions relative to thetreatment volume 32 such that the radiation beams travel throughdifferent tissues en route to the treatment volume 32. Ideally, theprimary routes to the treatment volume should include certain “treatmentportals” that do not include sensitive structures and therefore canaccept a larger radiation dose. In this fashion, the radiation therapymachine 40 is programmed to properly deliver the radiation dose to thetreatment volume 32. Definition of the treatment volume 32 and creationof the treatment plan may include an assessment of sensitive regions(e.g. radiosensitive tissues) proximate to the desired treatment volumeand according modifications to the treatment volume 32 and/or treatmentplan to ensure a lower radiation dose to sensitive areas.

Once the treatment volume 32 has been defined, and the treatment plancreated, the patient may be positioned on the table 52 for delivery ofradiation to the treatment volume 32. Prior to delivery of theradiation, the location of the patient may be identified utilizing theon-board CT scanner or other type of imaging device on a similarmachine. Verification of the position of the patient is especiallyimportant due to the proximity of sensitive structures in the spine.Once the patient's position has been verified, the radiation therapymachine 40 may be used to deliver the prescribed radiation dose to thetreatment volume 32.

The utilization of radiation to treat discogenic pain requires theprogramming of treatment planning software used to control the radiationtherapy machine 40 in order to deliver radiation to the treatment volume32. While radiation therapy is presently used to treat tumors found inthe spine, such tumors are not typically found in the intervertebraldiscs. In one embodiment of the invention, similar doses and radiationenergies are used to treat discogenic pain as are presently used incancer treatments, but the radiation dose necessary to depopulate and/orinactivate the offending nociceptors 30 and/or eliminate invadingvasculature may differ from the radiation dose necessary to kill tumorcells. Therefore, a lower radiation dose may be used to treat discogenicpain as compared to the total overall doses used to treat tumors.Fractionation may also be utilized in radiation treatment of discogenicpain.

Utilization of radiation therapy machine 40 to treat discogenic pain isnon-invasive and may use currently available radiation therapy equipmentwith modifications in accordance with the invention described herein. Inan exemplary embodiment, the radiation therapy machine 40 is owned by amedical clinic, such as a clinic specializing in the treatment of backpain. A patient may contact the clinic to set up an appointment to visitthe clinic for diagnosis and/or treatment of the back pain, perhaps inresponse to advertisements or information provided by the clinic orother organization (e.g. advertisements in magazines, in newspapers, onbillboards, or via television, radio, or the internet). Multipletreatment visits will be necessary in the case of a fractionatedtreatment plan.

Because conformal radiotherapy using machines such as the TomoTherapyHI-ART® or Accuray CYBERKNIFE® systems identified above delivers aradiation dose to a defined three-dimensional volume within the bodywhile sparing proximate tissues to the extent possible, it may bepossible to treat discogenic symptoms using radiation therapy whereconventional surgical methods are unavailable. Further still,utilization of radiation therapy does not have the inherent risksassociated with conventional spine surgery options, such as the spinalfusion surgical procedures that are currently utilized to treat chroniclower back pain.

While the detailed drawings and specific examples given herein describevarious exemplary embodiments, they serve the purpose of illustrationonly. It is to be understood that the invention is not limited in itsapplication to the details of construction and the arrangements ofcomponents set forth in the preceding description or illustrated in thedrawings. For example the methods may be performed in a variety ofsequences of steps. Furthermore, other substitutions, modifications,changes, and omissions may be made in the design, operating conditions,and arrangements of the exemplary embodiments without departing from thescope of the invention as expressed in the appended claims.

1. A method of treating discogenic back pain in a patient, comprising:acquiring an image of at least a portion of the patient's spine;locating the spinal disc causing the back pain; defining a treatmentvolume encompassing at least a portion of one or more nervestransmitting impulses that result in the sensation of the back paincaused by the spinal disc; prescribing a radiation dose to be deliveredto the treatment volume; providing a radiation therapy machine;positioning the patient in the radiation therapy machine; configuringthe radiation therapy machine to deliver the radiation dose to thetreatment volume; and delivering the radiation dose to the portion ofone or more nerves within the treatment volume.
 2. The method of claim1, wherein the image is acquired using at least one of a computedtomography scanner and an MRI system.
 3. The method of claim 1, whereinthe delivering the radiation dose step comprises delivering a portion ofthe radiation dose in each of multiple treatment sessions until thetotal radiation dose has been delivered.
 4. The method of claim 1,wherein the radiation therapy machine uses a linear accelerator toproduce radiation.
 5. The method of claim 1, wherein the delivering theradiation dose step comprises delivering multiple beams of radiation tothe treatment volume from different directions.
 6. The method of claim1, further comprising injecting a fluid into the treatment volume toconcentrate the effect of the radiation.
 7. The method of claim 1,further comprising: identifying a radiosensitive area; and configuringthe radiation therapy machine to avoid the radiosensitive area whendelivering the radiation dose.
 8. The method of claim 7, wherein theradiosensitive area is avoided by delivering the radiation dose throughone or more treatment portals extending through non-radiosensitive areasto reach the treatment volume.
 9. The method of claim 1, wherein theradiation therapy machine utilizes x-rays or gamma rays to deliver theradiation dose to the treatment volume.